The present invention relates to an image-capturing apparatus and an imager, and specifically relates to an image-capturing apparatus, such as an electronic still camera, etc., in which an electronic shutter function and a light detecting function of the solid-state imager is utilized for controlling an exposure amount, and an imager employed for the image-capturing apparatus.
Thanks to the recent development of the electronic technology, electronic still cameras including digital still cameras, which can convert a photo-image to image data and can store the image data, have been developed and proliferated in the market. Incidentally, in the conventional electronic still cameras, a photometry conducted by the imager is commenced when the release switch is pushed to a half-stroke, and then, an image-capturing is conducted at a shutter speed and an aperture determined on the basis of the photometry result when the release switch is pushed to a full-stroke. Further, to cope with such a case that a sufficient reflected light cannot be returned from the subject when capturing images in a room or a night, the conventional electronic still cameras incorporate an automatic intensity-adjusting strobe.
In the automatic intensity-adjusting strobe having a photo-sensor, such as a photo-diode, etc., disposed in the vicinity of the strobe or the lens, the exposure amount is controlled in such a manner that the photo-sensor detects an amount of reflected light when the light emitted by the strobe is reflected from the subject and the light emitting action of the strobe is deactivated when the amount of reflected light reaches to an appropriate amount.
Incidentally, for instance, in the cameras set forth in Tokkouhei 6-87582 and Tokkouhei 6-71323, an amount of reflected strobe light is detected by an exclusive photo-sensor, while an exposure amount is controlled by an action of the electronic shutter in the imager, instead of the deactivation of the strobe light.
On the other hand, when capturing a scene in which the subject brightness is currently varying, there is a fear that a field brightness at the stage of pushing the release switch to a half-stroke is different from that at the stage of pushing the release switch to a full-stroke, resulting in an inappropriate exposure amount.
In some of cameras in which the release switch has not the half-stroke mode, both photometry and ranging are commenced at the time of operating the release switch, and immediately after completing the photometry and ranging, exposing operation is conducted. In this case, since a time lag is generated between the time of pushing the release switch and the time of exposing the scene, there is a fear that the scene actually photographed is different from the scene that the photographer really intended to capture, due to a change of the subject posture within the time lag, etc.
To overcome the abovementioned problem, a photometry element, which allows a camera to conduct a photometry operation during the photo-electronic conversion performed in the imager when pushing the release switch, has been separately equipped in the camera. In such the camera, the shutter speed can be set at either a fast or a slow mode corresponding to the change of the field brightness, resulting in an appropriate exposing operation. It has been a problem, however, that the photometry element separately equipped in the camera would raise the cost of electronic still camera and would make the size of the camera larger.
Further, there has been a well-known camera that repeatedly conducts photometry operations when the power switch is turned on, and captures an image in response to the pushing action of the release switch. According to such the camera, since the photometry operations are conducted before the pushing action of the release switch, it becomes possible to conduct a more appropriate exposing operation by, for instance, finding an average value of the brightness, even if the field brightness of the scene would vary during the image-capturing operation. Such the camera, however, is apt to consume a large amount of electronic power since photometry operations are successively performed after the release switch is pushed, and as a result, a number of captured images is limited to a relatively small number when a battery is employed as a power source.
On the other hand, during the time period from a time when the power switch is turned on to a time when the power switch is turned off, a power dissipation is continues due to a faint electronic current flowing into the electronic circuit of the camera. To suppress such the unnecessary power dissipation, there has been developed a camera, in which the power-supplying operation is automatically deactivated in case that the release switch has not been pushed during a predetermined time-interval after the power switch was turned on. Even such the camera, however, surely consumes electronic power during the predetermined time-interval after the power switch was turned on. Accordingly, there has been desired to develop a configuration of a camera that can suppress the power consumption mentioned above.
Incidentally, in order to incorporate the automatic intensity-adjusting strobe in the camera, it is necessary to dispose the photo-sensor at a front side of the electronic still camera other than the light-emitting section of strobe light. Accordingly, it has been a problem that a space for disposing the photo-sensor should be located at an appropriate position. Specifically, since promoting the minimization of the product and the priority of good design have tended to be a mainstream of the design concept, it has been increasingly become difficult to find the appropriate position for mounting even a very small part. In addition, other than the photo-sensor, it is necessary to employ a semiconductor element for shorting a voltage applied to a strobe-light emitting tube so as to stop emitting the strobe light. Such the semiconductor element would raise the cost of the product.
Further, in case that the exposure-controlling operation is performed in the solid-state imager by employing the technologies set forth in the aforementioned official gazettes, although the semiconductor element for stopping the emission of the strobe light can be excluded, at least the photo-sensor is still required. Accordingly, aforementioned problems in regard to the space and the cost could not be solved.
Still further, when the photo-sensor is employed, sometimes, the actual image-capturing range deviates from the detecting range of the strobe light, since an angle of incidence or a direction of incidence varies depending on variations of mounting accuracy. Accordingly, it has been a problem that an accurate adjustment of the strobe light becomes difficult, or requires laborious adjusting operations.